Average heterozygosity per locus in humans will continue to be studied by double-label autoradiography of two-dimensional polyacrylamide gel patterns obtained from fibroblasts and/or lymphocytes. A technique for gentle separation of proteins from nucleic acids and phospholipids has been devised, which will facilitate identification of 32P-phosphoproteins by autoradiography of two-dimensional gel patterns, free of contaminating radioactivity in other types of macromolecules and lipids. The technique will be applied to several cell systems in the coming year. Efforts to organize a Human Protein Index Program for the clinical application of high-resolution two-dimensional polyacrylamide gels will be continued in collaboration with scientists at Argonne National Laboratory and elsewhere.